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DJ Mauretto



Joined: 14 Mar 2007
Posts: 464
Location: Rome,Italy
DJ Mauretto
If you really want to experiment with the bios you have to buy a chip equal to that of your mother board and program, then replace the chip and have fun.
'Hello BIOS'

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Post 09 Aug 2010, 16:57
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
Alphonso wrote:
That's cool. Must be awkward though with so much of the BIOS shrouded in secrecy. Not sure why there seems to be so much information that needs to be under NDA such as the BIOS writers guide and then there's probably some more that doesn't come under that either. Sad

Actually, no secrecy or NDA. Old ("legacy") BIOSes were shrouded in secrecy, UEFI has most of interfaces described in documents accessible after registration at uefi.org (unless you consider some "I accept terms" to be NDA).

Quote:
Haven't played with the BIOS for a while but have thought it might be cool to write some BIOS code. Nothing too extravagant, simple initializing and debug output maybe. At least I'd get a look at the CPU initial state. Shame my laptop doesn't have a serial port. Do you think this would be fairly easy? Would you have any recommendation for a suitable emulator for BIOS code?

I have little experience with these stuff myself, and I think it will be fairly hard. There are too many things that need to be initialized in order to get to state where you can execute "normal" code.
Post 09 Aug 2010, 18:19
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shoorick



Joined: 25 Feb 2005
Posts: 1605
Location: Ukraine
shoorick
Post 10 Aug 2010, 04:36
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Alphonso



Joined: 16 Jan 2007
Posts: 294
Alphonso
[quote="vid"]
Alphonso wrote:
Actually, no secrecy or NDA.
I was thinking more along the lines of hardware. There's a heap of registers missing from the public Intel documentation. I wouldn't be looking at making a fully fledged BIOS so not worried about running "normal" code. Too much for just one person I think. Wink

Yeah shoorick, if I do it, it would be something like that, really basic (at least to start with). Not having a serial or parallel port is a bummer though. I wonder how much I could do without initializing RAM let alone graphics, drives, keyboard etc. Maybe I could find a GPIO I could use for communication / debug output. Then again there might be the possibility of a (mini) pci debug card and port 80h.
Post 10 Aug 2010, 07:33
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
Quote:
I was thinking more along the lines of hardware. There's a heap of registers missing from the public Intel documentation.

Actually, vast majority is described, but in a way that doesn't make one very smart. It would need some "theoretical introduction" (big picture how things work and cooperate), like CPU manuals have.
Post 10 Aug 2010, 09:58
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